1. Field of the Invention
The present invention relates to contact of gas containing sulfur dioxide and particulate matter with finely dispersed slurry of lime/limestone. More particularly the invention relates to directing the gas to be contacted in a circular path through which a slurry of lime/limestone is sprayed while the gas in the entrance and gas in the exit of the path are maintained in a heat exchange relationship.
2. Description of the Prior Art
Regulatory agencies are limiting the emissions from oil and coil-fired cumbustion equipment. The foremost pollutants are sulfur dioxide and particulate matter. For example, a common limit on SO.sub.2 emissions is 1.2 pounds SO.sub.2 /10.sup.6 BTU heat input.
Various methods and systems to scrub pollutants from emissions have been used in the past, but the effectiveness of each is limited. Wet scrubbers provide the most effective means for controlling both the gaseous and particulate emissions. A number of different chemicals have been tried in wet scrubbers for enhancing the absorption of SO.sub.2. The most versatile chemical has been lime/limestone because of its availability and low cost. However, the wet scrubber designs using lime/limestone presently available, suffer from various problems. Gas side pressure drop, liquid pumping power requirement, scaling and plugging within the scrubber, liquid carry-over with the scrubbed gas, and gas reheat have been some of the major costs and problems associated with the development of wet scrubber technology.
There is need for (1) increased effectiveness in the contact between the gas and the liquid so as to lower the liquid pumping power requirement, (2) low gas-side pressure drop by minimizing restrictions in gas flow, (3) minimizing the plugging and scaling potential by minimizing the scrubber internals, (4) minimizing the liquid entrainment with the scrubbed gas, and (5) providing a means for re-heating the scrubbed gas without having to use premium fuels such as natural gas and oil.